gamma-Linolenic acid-containing diet attenuates bleomycin-induced lung fibrosis in hamsters

Insights into the Role of Bioactive Food Ingredients and the Microbiome in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease mainly associated with aging and, to date, its causes are still largely unknown. It has been shown that dietary habits can accelerate or delay the occurrence of aging-related diseases; however, their potential role in IPF development has been underestimated so far. The present review summarizes the evidence regarding the relationship between diet and IPF in humans, and in animal models of pulmonary fibrosis, in which we discuss the bioactivity of specific dietary food ingredients, including fatty acids, peptides, amino acids, carbohydrates, vitamins, minerals and phytochemicals. Interestingly, many animal studies reveal preventive and therapeutic effects of particular compounds. Furthermore, it has been recently suggested that the lung and gut microbiota could be involved in IPF, a relationship which may be linked to changes in immunological and inflammatory factors. Thus, all the evidence so far puts forward the idea that the gut-lung axis could be modulated by dietary factors, which in turn have an influence on IPF development. Overall, the data reviewed here support the notion of identifying food ingredients with potential benefits in IPF, with the ultimate aim of designing nutritional approaches as an adjuvant therapeutic strategy.

Advances in Our Understanding of Oxylipins Derived from Dietary PUFAs

Oxylipins formed from polyunsaturated fatty acids (PUFAs) are the main mediators of PUFA effects in the body. They are formed via cyclooxygenase, lipoxygenase, and cytochrome P450 pathways, resulting in the formation of prostaglandins, thromboxanes, mono-, di-, and tri-hydroxy fatty acids (FAs), epoxy FAs, lipoxins, eoxins, hepoxilins, resolvins, protectins (also called neuroprotectins in the brain), and maresins. In addition to the well-known eicosanoids derived from arachidonic acid, recent developments in lipidomic methodologies have raised awareness of and interest in the large number of oxylipins formed from other PUFAs, including those from the essential FAs and the longer-chain n-3 (ω-3) PUFAs. Oxylipins have essential roles in normal physiology and function, but can also have detrimental effects. Compared with the oxylipins derived from n-3 PUFAs, oxylipins from n-6 PUFAs generally have greater activity and more inflammatory, vasoconstrictory, and proliferative effects, although there are notable exceptions. Because PUFA composition does not necessarily reflect oxylipin composition, comprehensive analysis of the oxylipin profile is necessary to understand the overall physiologic effects of PUFAs mediated through their oxylipins. These analyses should include oxylipins derived from linoleic and α-linolenic acids, because these largely unexplored bioactive oxylipins constitute more than one-half of oxylipins present in tissues. Because collated information on oxylipins formed from different PUFAs is currently unavailable, this review provides a detailed compilation of the main oxylipins formed from PUFAs and describes their functions. Much remains to be elucidated in this emerging field, including the discovery of more oxylipins, and the understanding of the differing biological potencies, kinetics, and isomer-specific activities of these novel PUFA metabolites.

Following the path of CCL2 from prostaglandins to periostin in lung fibrosis

Without question, the greatest and most humbling honor of my scientific career was to learn that I was nominated for the American Thoracic Society Recognition Award for Scientific Accomplishments. On the occasion of this award, as I look back on the progress made in the last 15 years, I am pleased by the scientific insights; however, I am also saddened that we still have no internationally recognized efficacious therapy. This perspective will highlight the areas my laboratory has addressed regarding the pathogenesis of idiopathic pulmonary fibrosis in hopes of identifying new therapeutic targets.

Dietary Flaxseed Oil Protects against Bleomycin-Induced Pulmonary Fibrosis in Rats

Bleomycin, a widely used antineoplastic agent, has been associated with severe pulmonary toxicity, primarily fibrosis. Previous work has shown a reduction in bleomycin-induced lung pathology by long-chain omega-3 fatty acids. Treatment by short-chain omega-3 fatty acids, α-linolenic acid, found in dietary flaxseed oil may also reduce lung fibrosis, as previously evidenced in the kidney. To test this hypothesis, 72 rats were divided between diets receiving either 15% (w/w) flaxseed oil or 15% (w/w) corn oil (control). These groups were further divided to receive either bleomycin or vehicle (saline) via an oropharyngeal delivery, rather than the traditional intratracheal instillation. Lungs were harvested at 2, 7, and 21 days after bleomycin or saline treatment. Animals receiving flaxseed oil showed a delay in edema formation (P = 0.025) and a decrease in inflammatory cell infiltrate and vasculitis (P = 0.04 and 0.007, resp.). At days 7 and 21, bleomycin produced a reduction in pulmonary arterial lumen patency (P = 0.01), but not in rats that were treated with flaxseed oil. Bleomycin-treated rats receiving flaxseed oil had reduced pulmonary septal thickness (P = 0.01), signifying decreased fibrosis. Dietary flaxseed oil may prove beneficial against the side effects of this highly effective chemotherapeutic agent and its known toxic effects on the lung.

Opposing roles of leukotrienes and prostaglandins in fibrotic lung disease

Lung fibrosis is a devastating disease that involves a variable degree of inflammation, alveolar epithelial injury, fibroblast hyperplasia and the deposition of extracellular matrix. Standard therapies that consist of corticosteroids and immunosuppressive agents offer little benefit and most patients experience a progressive deterioration in lung function which is ultimately fatal within 2-5 years of diagnosis. New pathogenetic insights and therapeutic approaches are badly needed. Eicosanoids are lipid mediators derived from arachidonic acid metabolism, the best studied of which are prostaglandins and leukotrienes. Although these mediators are primarily known for their roles in asthma, pain, fever and vascular responses, they also exert relevant effects on immune and inflammatory cells as well as structural cells such as epithelial cells and fibroblasts - cell types which participate in fibrogenesis. In general, leukotrienes promote while prostaglandin E(2) opposes fibrogenic responses. Lung fibrosis is associated with increased production of leukotrienes and decreased production of prostaglandin E(2). Furthermore, responses to prostaglandin E(2) are altered in fibrotic conditions. This review highlights the role of this leukotriene/prostaglandin imbalance in the evolution of fibrotic lung disease, offers insights into the mechanisms that underlie the dysregulated responses and discusses approaches for therapeutic targeting of eicosanoids in these conditions.

The bleomycin animal model: a useful tool to investigate treatment options for idiopathic pulmonary fibrosis?

Different animal models of pulmonary fibrosis have been developed to investigate potential therapies for idiopathic pulmonary fibrosis (IPF). The most common is the bleomycin model in rodents (mouse, rat and hamster). Over the years, numerous agents have been shown to inhibit fibrosis in this model. However, to date none of these compounds are used in the clinical management of IPF and none has shown a comparable antifibrotic effect in humans. We performed a systematic review of publications on drug efficacy studies in the bleomycin model to evaluate the value of this model regarding transferability to clinical use. Between 1980 and 2006 we identified 240 experimental studies describing beneficial antifibrotic compounds in the bleomycin model. 222 of those used a preventive regimen (drug given < or =7 days after last bleomycin application), only 13 were therapeutic trials (>7 days after last bleomycin application). In 5 studies we did not find enough details about the timing of drug application to allow inter-study comparison. It is critical to distinguish between drugs interfering with the inflammatory and early fibrogenic response from those preventing progression of fibrosis, the latter likely much more meaningful for clinical application. All potential antifibrotic compounds should be evaluated in the phase of established fibrosis rather than in the early period of bleomycin-induced inflammation for assessment of its antifibrotic properties. Further care should be taken in extrapolation of drugs successfully tested in the bleomycin model due to partial reversibility of bleomycin-induced fibrosis over time. The use of alternative and more robust animal models, which better reflect human IPF, is warranted.

Pharmacological inhibition of leukotrienes in an animal model of bleomycin-induced acute lung injury

Leukotrienes are increased locally in idiopathic pulmonary fibrosis. Furthermore, a role for these arachidonic acid metabolites has been thoroughly characterized in the animal bleomycin model of lung fibrosis by using different gene knock-out settings.

We investigated the efficacy of pharmacological inhibition of leukotrienes activity in the development of bleomycin-induced lung injury by comparing the responses in wild-type mice with mice treated with zileuton, a 5-lipoxygenase inhibitor and MK-571, a cys-leukotrienes receptor antagonist.

Mice were subjected to intra-tracheal administration of bleomycin or saline and were assigned to receive either MK-571 at 1 mg/Kg or zileuton at 50 mg/Kg daily. One week after bleomycin administration, BAL cell counts, lung histology with van Gieson for collagen staining and immunohistochemical analysis for myeloperoxidase, IL-1 and TNF-α were performed.

Following bleomycin administration both MK-571 and zileuton treated mice exhibited a reduced degree of lung damage and inflammation when compared to WT mice as shown by the reduction of:(i) loss of body weight, (ii) mortality rate, (iii) lung infiltration by neutrophils (myeloperoxidase activity, BAL total and differential cell counts), (iv) lung edema, (v) histological evidence of lung injury and collagen deposition, (vi) lung myeloperoxidase, IL-1 and TNF-α staining.

This is the first study showing that the pharmacological inhibition of leukotrienes activity attenuates bleomycin-induced lung injury in mice. Given our results as well as those coming from genetic studies, it might be considered meaningful to trial this drug class in the treatment of pulmonary fibrosis, a disease that still represents a major challenge to medical treatment.

Effects of fish oil treatment on bleomycin-induced pulmonary fibrosis in mice

Bleomycin is an antibiotic used to treat a variety of neoplasms. A major side-effect of bleomycin therapy is the induction of an intense inflammatory response that develops into pulmonary fibrosis. Several studies have shown that certain polyunsaturated fatty acids found in fish oil reduce the inflammatory response in vivo. Fish oil has been employed for the treatment of several pathologies such as glomerulonephritis, cardiovascular diseases, rheumatoid arthritis, and even as an adjuvant in cancer therapy. This study examined the effects of fish oil treatment on the development of bleomycin-induced pulmonary fibrosis. Mice were intraperitoneally treated with bleomycin or with saline daily for 10 days, and 15 days after the last injection they started to receive fish oil by gavage for 14 days. The lungs were processed for light microscopy, biochemical and immunohistochemical investigations. Fish oil did not prevent the development of pulmonary fibrosis after the injury as shown by light microscopy, cytokines immunohistochemical analysis, TBARS content and protein levels in the lung. In addition however, fish oil itself induced a slight inflammatory process in the lung, as observed by the increase in cellularity, vasodilatation in the lung parenchyma, TBARS content, and a slight increase in the lung protein content.

Dietary gamma-linolenate attenuates tumor growth in a rodent model of prostatic adenocarcinoma via suppression of elevated generation of PGE(2) and 5S-HETE

Prostate cancer poses considerable threat to the aging male population as it has become a leading cause of cancer death to this group. Due to the complexity of this age-related disease, the mechanism(s) and factors resulting in prostate cancer remain unclear. Reports showing an increase risk in prostatic cancer with increasing dietary fat are contrasted by other studies suggesting the beneficial effects of certain polyunsaturated fatty acid (PUFA) in the modulation of tumor development. The n-6 PUFA, gamma-linolenic acid (GLA), has been shown to suppress tumor growth in vitro. Therefore, using the Lobund-Wistar (L-W) rat model of prostate cancer, we tested the hypothesis whether dietary supplementation of GLA could suppress tumor growth and development in vivo. Prostatic adenocarcinomas were induced in two groups of L-W rats, the experimental group (N-nitroso-N-methylurea, NMU/testosterone propionate, TP) and the GLA group (NMU/TP/GLA fed) undergoing similar treatment but fed a purified diet supplemented with GLA. Our findings revealed a decrease in prostate growth in the NMU/TP/GLA-fed group as determined by weight, tissue size, DNA content and prostate-specific antigen (tumor marker of prostate cancer). Comparison between the two groups showed a significant increase in 5S-hydroxyeicosatetraenoic acid and prostaglandin E(2) in the NMU/TP group. These increases paralleled the increased protein expression and activity of cyclooxygenase-2 as well as increased activity of 5-lipoxygenase. Taken together, the findings showed that intake of GLA-enriched diet does reduce prostatic cancer development in L-W rats and could serve as a non-toxic adjunct in management of human prostatic cancer.

Eicosanoids: mediators and therapeutic targets in fibrotic lung disease

Fibrosis is a common end-stage sequella of a number of acute and chronic lung diseases. Current concepts of pathogenesis implicate dysregulated interactions between epithelial cells and mesenchymal cells. Although investigative efforts have documented important roles for cytokines and growth factors in the pathogenesis of fibrotic lung diseases, these observations have not as yet been translated into efficacious therapies, and there is a pressing need for new pathogenetic insights and therapeutic approaches for these devastating disorders. Eicosanoids are lipid mediators derived from arachidonic acid, the most studied of which are the prostaglandins and leukotrienes. Although they are primarily known for their roles in asthma, pain, fever and vascular responses, present evidence indicates that eicosanoids exert relevant effects on immune/inflammatory, as well as structural, cells pertinent to fibrogenesis. In general, leukotrienes promote, whereas prostaglandin E(2) opposes, fibrogenic responses. An imbalance of eicosanoids also exists in pulmonary fibrosis, which favours the production of leukotrienes over prostaglandin E(2). This review highlights the role of this imbalance in the evolution of fibrotic lung disease, discusses the mechanisms by which it may arise and considers approaches for therapeutic targeting of eicosanoids in these conditions.

Changes in the fatty acid composition and hydroxyproline content in rat lung in relation to collagen synthesis after paraquat administration

OBJECTIVES

Effect of paraquat on the fatty acid composition (weight percentage) of rat lung was studied with particular reference to the change of hydroxyproline content in the course of paraquat-induced dysfunction and subsequent repair.

METHODS

Eight-week-old male Wistar rats were administered paraquat at 20 mg/kg body weight subcutaneously, and the wet weight, hydroxyproline content and fatty acid composition of lungs of each group rats were analyzed at 2, 7, 14 or 28 days after treatment, respectively.

RESULTS

The percentage of palmitic acid (C16:0), arachidonic acid (C20:4) and docosahexaenoic acid (C22:6) significantly increased, and the percentage of oleic acid (C18:1) and the ratio of monounsaturated fatty acids/saturated fatty acids (M/S) significantly decreased comparing to control on day 28 after paraquat administration. The time-course of each fatty acid was observed for 28 days after paraquat administration. M/S ratio decreased after paraquat administration up to the 28th day, but the polyunsaturated fatty acids/saturated fatty acids (P/S) ratio decreased during the first 7 days, followed by a increase, and then reached higher level than the 0 day control at the 28th day. Hydroxyproline also increased between the 14th and the 28th days. Eicosapentaenoic acid (C20:5) had once increased during the first 2 days and decreased gradually, while C20:4 maintained high level in this period. C22:6 increased after paraquat administration and maintained high level up to the 28th day. This result indicated that desaturation and elongation in n-3 series fatty acids were accelerated after paraquat treatment, and consequently C20:5 was rapidly converted into C22:6 and decreased.

CONCLUSIONS

Paraquat might cause elevation of unsaturated fatty acids, espe- cially C20:4 but not C20:5 by the stimulation of the fatty acid desaturase system, and could consequently stimulate local collagen synthesis by C20:4 metabolites in the healing stage.

Novel pharmacological approaches to manage interstitial lung fibrosis in the twenty-first century

Pharmacological agents currently in use to treat interstitial lung fibrosis are either ineffective or too toxic in humans. This review addresses mechanistically based novel approaches that have the potential to minimize the accumulation of collagen in the lung, a hallmark of lung fibrosis. These approaches include maintaining the intracellular levels of NAD(+) and ATP, blocking the biological activities of TGF-beta and integrins, evaluating the effectiveness of PAF-receptor antagonists and NOS inhibitors, and developing a new generation of cysteine pro-drugs with an adequate degree of bioavailability. A critical analysis of each approach as it relates to management of IPF in humans is presented.

Biological significance of essential fatty acids/prostanoids/lipoxygenase-derived monohydroxy fatty acids in the skin

The skin displays a highly active metabolism of polyunsaturated fatty acids (PUFA). Dietary deficiency of linoleic acid (LA), an 18-carbon (n-6) PUFA, results in characteristic scaly skin disorder and excessive epidermal water loss. Although arachidonic acid (AA), a 20-carbon (n-6) PUFA, is metabolized via cyclooxygenase pathway into predominantly prostaglandin E2 (PGE2) and PGF2alpha, the metabolism of AA via the 15-lipoxygenase (15-LOX) pathway, which is very active in skin epidermis and catalyzes the transformation of AA into predominantly 15S-hydroxyeicosatetraenoic acid (15S-HETE). Additionally, the 15-LOX also metabolizes the 18-carbon LA into 13S-hydroxyoctadecadienoic acid (13S-HODE), respectively. Interestingly, 15-LOX catalyzes the transformation of dihomo-gamma-linolenic acid (DGLA), derived from dietary gamma-linolenic acid, to 15S-hydroxyeicosatrienoic acid (15S-HETrE). These monohydroxy fatty acids are incorporated into the membrane inositol phospholipids which undergo hydrolytic cleavage to yield substituted-diacylglycerols such as 13S-HODE-DAG from 13S-HODE and 15S-HETrE-DAG from 15S-HETrE. These substituted-monohydroxy fatty acids seemingly exert anti-inflammatory/antiproliferative effects via the modulation of selective protein kinase C as well as on the upstream/down-stream nuclear MAP-kinase/AP-1/apoptotic signaling events.

5 alpha-reductase-catalyzed conversion of testosterone to dihydrotestosterone is increased in prostatic adenocarcinoma cells: suppression by 15-lipoxygenase metabolites of gamma-linolenic and eicosapentaenoic acids

Although the androgens, testosterone (T) and its highly active metabolite dihydrotestosterone (DHT) play a role in the development and progression of prostate cancer, the mechanism(s) are unclear. Furthermore, 5 alpha-reductase which catalyze the conversion of T to DHT, has been a target of manipulation in the treatment of prostatic cancer, hence synthetic 5 alpha-reductase activity inhibitors have shown therapeutic promise. To demonstrate that nutrients derived from dietary sources can exert similar therapeutic promise, this study was designed using benign hyperplastic cells (BHC) and malignant tumorigenic cells (MTC) derived from Lobund-Wistar (L-W) rat model of prostatic adenocarcinoma to test the effects of gamma-linolenic acid (GLA), eicosapentaenoic acid (EPA) and their 15-lipoxygenase metabolites on cellular 5 alpha-reductase activity. Our data revealed: (i) that incubation of MTC with [3H]-T resulted in marked conversion to [3H]-DHT when compared to similar incubation with BHC; (ii) that DHT-enhanced activity of 5 alpha-reductase was inhibited 80% by 15S-hydroxyeicosatrienoic acid, the 15-lipoxygenase metabolite of GLA, when compared to 55% by 15S-hydroxyeicosapentaenoic acid, the 15-lipoxygenase metabolite of EPA; and (iii) that their precursor fatty acids, respectively, exerted moderate inhibition. Taken together, the study underscores the biological importance of 15-lipoxygenase metabolites of polyunsaturated fatty acids (PUFAs) in androgen metabolism.

Protection from pulmonary fibrosis in leukotriene-deficient mice

Although overproduction of proinflammatory 5-lipoxygenase (5-LO)-derived leukotrienes (LTs) has been demonstrated in the lungs of patients with pulmonary fibrosis, their causal involvement in this condition has not been established. Bleomycin-induced pulmonary fibrosis was studied in mice rendered LT deficient by knockout of the 5-LO gene (KO) and in wild-type (WT) control mice. Following administration of bleomycin, lung lavage fluid of WT mice demonstrated an approximately 5-fold increase in levels of cysteinyl-LTs over baseline levels at Day 1, with persistent elevation up to Day 21. As compared with WT mice, 5-LO KO mice demonstrated reduced amounts of histologically evident collagen as well as an approximately 60% reduction in lung hydroxyproline levels postbleomycin. Unlike WT mice, KO mice showed no increases in the numbers of lung inflammatory cells postbleomycin. Furthermore, in situ expression and stimulated production by mixed lung leukocytes of the antifibrotic cytokine interferon-gamma were significantly greater in cells from the 5-LO KO mice. Finally, lavage levels of the antiinflammatory and antifibrotic molecule, prostaglandin E(2), were significantly greater in the KO animals. These results provide strong evidence that LTs may participate in the pathogenesis of pulmonary fibrosis, and they may do so by direct effects as well as indirect effects occurring via their modulation of the synthesis of other inflammatory mediators.

Modification of doxorubicin-induced cardiotoxicity: effect of essential fatty acids and ICRF-187 (dexrazoxane)

The capacity of an oil, containing gamma-linolenic acid (GLA), to reduce the severity of doxorubicin-induced cardiotoxicity has been investigated in a rat model. Groups of 12-week-old, male, Sprague-Dawley rats were injected intravenously (i.v.) with single doses (3 mg/kg body weight) of doxorubicin (DOX). Daily for 1 week prior to DOX administration and for up to 20 weeks afterwards groups of rats received either an oil containing both GLA and linoleic acid (So-1100, Scotia Pharmaceuticals), at two dose levels, or an oil containing linoleic acid, but no GLA (So-1129) by oral gavage. Other groups of rats received water as a control. One of the groups of rats that received water also received i.v. ICRF-187 (60 mg/kg) 15 min prior to DOX. A group of animals acted as age-matched controls. The maximum reduction in body weight in the first 2 weeks after the administration of DOX. was used as a measure of acute toxicity. This was most severe in the group receiving a combination of DOX and ICRF-187 (5.6+/-0.43%). Animals receiving 2 ml of either So-1100 or So-1129 were the least affected ( approximately 2.5%). Measurements of cardiac volume output made at various intervals after DOX administration indicated a approximately 35% reduction in cardiac function in the control and So-1129 oil group after 20 weeks. The corresponding reduction in the groups receiving ICRF-187 and 2 ml of So-1100 was approximately 16%. The group receiving daily doses of 1 ml So-1100 showed an intermediate response. The death of an animal with signs of congestive cardiac failure occurred in 40% of the animals in the DOX only control (water) group. There were no deaths in the groups of rats receiving either ICRF-187 or pre- and post-administration of 2 ml of So-1100. It was concluded that an oil containing GLA (So-1100) has similar cardioprotective properties against DOX-induced cardiotoxicity as ICRF-187, but with less general toxicity in this rat model.

Significance of lipoxygenase-derived monohydroxy fatty acids in cutaneous biology

The skin displays a highly active metabolism of polyunsaturated fatty acids (PUFA). Dietary deficiency of linoleic acid (LA), an 18-carbon (n-6) PUFA, results in characteristic scaly skin disorder and excessive epidermal water loss. Although arachidonic acid (AA), a 20-carbon (n-6) PUFA, is metabolized via cyclooxygenase pathway into predominantly prostaglandin E2 (PGE2) and PGF2alpha. The 15-lipoygenase is very active in this tissue and catalyzes the transformation of 20-carbon AA into predominantly 15-hydroxyeicosatetraenoic acid (15-HETE). Similarly, the epidermal 15-lipoxygenase also catalyzes the transformation of 18-carbon LA and 20-carbon dihomo-gamma-linolenic acid (DGLA) to 13-hydroxyoctadecadienoic acid (13-HODE) and 15-hydroxyeicosatrienoic acid (15-HETrE), respectively. The monohydroxy fatty acids are incorporated in phospholipids which undergo catalysis to yield substituted-diacylglycerols (13-HODE-DAG) and 15-HETrE-DAG) which exert anti-inflammatory/antiproliferative effects on the skin.

Suppression of proto-oncogene (AP-1) in a model of skin epidermal hyperproliferation is reversed by topical application of 13-hydroxyoctadecadienoic acid and 15-hydroxyeicosatrienoic acid

The present study was conducted to delineate whether a possible mechanism for 13-(S)-hydroxyoctadecadienoic acid (13-HODE) and 15-hydroxyeicosatrienoic acid (15-HETrE) reversal of experimentally-induced skin hyperproliferation in guinea pig is via the modulation of epidermal nuclear mitogen activator protein (AP-1), a nuclear transcription factor associated with tissue turnover. The data revealed that topical application of 13-HODE and/or 15-HETrE on the induced hyperproliferative skin reversed the hyperproliferation and up-regulated the suppressed AP-1 expression. A further analysis of the two major subunits of AP-1 (c-fos and c-jun) revealed a selective up-regulation of c-fos. These results underscore the modulatory role of lipoxygenase-derived hydroxy fatty acids on nuclear transcription factors and explains, at least in part, the antiproliferative effects of 13-HODE and 15-HETrE.

Clinical use of lipids to control inflammatory disease

Selective dietary supplementation with lipids has long been used to influence the course of chronic inflammatory diseases. This review describes new aspects of the molecular mechanism of lipids to modulate leukocyte activity and highlights some recent clinical studies on therapeutic lipid administration. New promising advances in parenteral application of lipids as well as the impact on acute inflammatory disorders are discussed.